Bearing Tips 01: Bearings are innocent until the contrary has been proven


Bearings manufactured today are of highest quality and do very seldom present defects that cause their failures!

This means that bearing failures are caused by external causes. Thus we do not depend on the manufacturers to avoid bearing failures but are ourselves responsible to prevent and correct bearing failures.

PictureBT01wbslBased on my experience the 10 mail causes for bearing failures are:

  1. Incorrect lubrication.
  2. Wrong bearing.
  3. Contamination.
  4. Misalignment.
  5. Wrong set-up (axially fixed and free bearings).
  6. Overload.
  7. Fitting practices (inadequate fits and mounting damages).
  8. False brinelling.
  9. Low quality of bearing seating.
  10. Electrical erosion.

Earlier many bearing failures occurred due to bearing quality issues as regards the materials, the manufacturing and the design, but the leading bearing manufacturers today apply cero defect strategy and the defects are measured only in some few ppm if any.

Thus as we now can rely on the bearing quality we have the opportunity to avoid bearing failures and improve their reliability and assume a proactive attitude and see bearing failures as challenges instead of problems to avoid further failures. It is completely different to analyse the failure to determine the required corrective actions and make a professional repair instead of just replace a “dam” bearing.

Take the opportunity to take the Bearing Failure Analysis Course announced on this site that now is ready and will be available within short (assessments also in Spanish, Swedish and to some extent in German).

As an example the above photo shows 2 single row angular contact ball bearing mounted in pair in a centrifugal pump. Wrong bearings as they were not adjusted for mounting in pair, thus the lack of 2 letters in the bearing designation caused an extremely expensive fire in a refinery, fortunately without any personal injuries in this case.

Per Arnold Elgqvist
[email protected]